Frank j



(No Model.) 2 SheetsSheer, 1.

P. J. SPRAGUE.

ELEOTRO DYNAMIC MOTOR.

No. 324,891. Patented Aug. 25, 1885.

w l ll 1: ii i i u i i'fiiliiiib (No Model.) 2 Sheets-Sheet 2.

F. J. SPRAGUE.

' ELECTED DYNAMIC MOTOR. No. 324,891. Patented Aug. 25, 18.85.

N. PETERS, Photo-Lilhographer. Wzuhingmn. 0,04

UNiTEio STATES PATENT OEErcE FRANK J. S PRAGUE, OF NEW YORK, N. Y., ASSIGNOR TO THE SPPAGUE HN\N"\ ELECTRIC RAILVAY AND MOTOR COMPANY.

ELECTRO-DYNAMIC MOTOR.

SPECIFICATION forming part of Letters Patent No. 324,891, dated August 25, 1885.

Application filed March 12, 1885. (No model.)

To aZZ whom it may concern: of the magnetic field and the cumulative Be it known that I, FRANK J. SPRAGUE, of series coils, so that their greatest effect is pro- New York, in the county and State of New duced on the other diagonally opposite parts.- York, have invented a certain new and useful The differential coils, are arranged to have a 55 Improvement in Electro-Dynamie Motors, of greater magnetizing effect than the cumulawhich the following is a spcciiication. tive coils. A decrease of load, causing a de- In my application, Serial No. 138,145, is set creased armature-current, tends to shift the forth an electro-dynamic motor, in which the magnetic resultant of the armature and heldnon-sparking points of the commutator-cylinmagnet; but this also decreases the mag- 6o 10 der are maintained constant by opposing the netizing effect of all the series coils, and theredistortion of the magnetic field due to variafore the parts of the field principally affected tions in the armature-current by a counterby the cumulative coils are weakened, and distortion dependent upon such variations, those principally affected by the differential whereby the magnetic resultant due to the coils are strengthened, whereby a distortion 65 r 5 armature and field-magnet is unchanged, and of tield is produced opposed to that produced the line of parallel cutting of the lines of force by the decrease of armattire-current, and hence or point of least sparking is maintained in the the magnetic resultantthe line of parallel same position. cuttingand the points of least sparkremains This invention relates to a simple construcunchanged. Thus no shifting of the commn- 7o tion for a motor whereby this counter-distortater-brushes is ever required, except on ac tion may be effectively produced. count of wear. At the same time as the dif- In carrying my invention into effect I emferential series coils predominate over the ploy main field-magnet coils in shunt relation cumulative, the whole field-magnet strength to the armature, dili'erential field-magnet is increased, and the speed of the motor is 75 coils in series with the armature, and additionbrought down to compensate forthc decreased al accumulative field magnet coils, also in load. series with the armature. The main field-coils The arrangement of two sets of series field may be shunted upon the armature alone, or coilsone diii'erential, the other cu1nulative upon the armature and both the cumulative may be employed simply as a means of field- So and differential series coils, or upon the regulation where it is not desired to produce 0 armature and either of said series coils, the the counter-distortion. In such case the coils other series coil remaining outside the termay be evenly wound on all the legs of the ininal of the main field-shunt. field-magnet and used only to regulate the The proportions of the winding of all the motor, being wound in the proportions above 85 5 field-magnet coils are preferably such as are set forth. The differential and cumulative set forth in my applications, Serial Nos. 138,- series coils have a differential eli'ect, which, 146 and ,13S,l47-that is, so that a zero-field as the diiterential coils predominate over the is produced if circuit is closed to the shunt cumulative coils, produces a weakening of the and series coils when the motor is at rest. totalstrcngth of the field magnet when the 0 This necessitates the employment of means armature-current increases, and a strengthenfor varying the magnetizing effect of the difingofthe fieldmagnet when the armaturecurt'erential coils. Such means are set forth in rent decreases, and so maintains constant the the applications just referred to, and will be speed of the motor, as set forth in the applihereinai'ter described. cations referred to. 95

5 In accomplishing the counter-distortion of My invention is illustrated in the annexed the field, the motor used is one in which the drawings, in which Figures 1 toS are diagrams field magnet cores extend in difi'erent direcillustrating various arrangementsofthcmotortions from the field of force in which the arcircuitswhich may be employed. Fig. 9 is a mature revolves. The differential series coils view of a motor embodying my invention; I00

50 are wound or arranged so that their greatest and Figs. 10, l], and 12 are diagrams illuseti'ectis produced on diagonally opposite parts trating the distortion of the magnetic field.

invention.

- being outside the terminal of the shunt.

In all these figures A is the armature, I3 the main or shunt field coils,() the differential series tield'coils, and l) the cumulative series fieldcoils. l 2 are the mains of a constant potential circuitwith which I prefer to employ my 3 4 are the motor-terminals, and 5 is a terminal of the armature or main fieldcoils shunt.

In Fig. 1 the main field-coils are shunted around the armature alone. In IJi 2 the main coils are shunted around the armature and the cumulative series coils alone, the difterentiial coils being outside the shunt-terminal. In Fig. 3 the shunt is around the armature and both the series sets. Fig. 4 is similar to Fig. 1, except that the positions of the two series sets are reversed. In Fi 5 the shunt is around the armature and the differential series coils, the cumulative series coils Fig. 6 is similar to Fig. 3, with the series coils reversed in position.

Fig. 7 shows means for varying the magnetizing effect of the differential series coils. Such means he e consist of a short-circuiting and reversing switch, E. In starting the motor this switch has the position shown, the current in the differential coils being thus reversed, and the 't'ield being, therefore, very strong when the motor starts. The position of the switch is then changed to short-circuit the series coil and so weaken the field-magnet,

I and finally the coils are thrown in direct, so

as to exert their usual effect.

In Fig. 8 the terminal 5 of the armatureshunt is shown shifted to a different point of the main field-coils. This may be done by any suitable commutator, and the difference ofpotential at the armature-shunt terminals and the current in the armature are thereby varied, and also, if the series coils are inside the shunt-terminals, asin this figure, themagnet izing effect of such coils is varied.

In Fig. 9, I is an elcctro-dynamic motor, like that represented in Fig. 6, the two sets of series coils being both inside the shunt-termt izals. The differential series coils are wound on two diagonally opposite legs of the fieldmagnet and the cumulative series coils on the other two legs. These coils act to regulate the speed of the motor under variable loads, and also to produce the counterdistortion and maintain the non sparking point constant in the manner which has been above explained. This is seen in Figs. 10, 11, and 12, wherein a- .r is the line of the magnetic resultant. In Fig. 10 this line is at its normal position. In Fig. 1.1 it is shifted, as shown by a change in the armatitre-current, due to a variation in load, while in Fig. 12 the line is brought back to its original position by the counter-distortion, as has been fully explained.

For convenience of illustration the armature shown in these three figures is a tiramine ring. N S are the field-magnet poles. The dotted lines in the interpolar space represent the magnetic lines of force.

What I claim is 1. In an electro-dynamic motor, the combination ofthc armature, main field-magnet coils in shunt relation to the armature, and dilferential. fiehlmagnet coils and cumulative fieldmagnet coils in series with the armature, substantially as set forth.

2. In an electro dynamic motor, the combination of the armature, a set of differential field-magnet coils, and a set of cumulative field magnet coils, both in series, with the armature and main field-magnet coils, shunted around one of said series sets, substantially as set forth.

3. In an electrodynamic motor, the combi nation of the armature, a set of differential field-magnet coils, and asetof cumulative field-magnet coils, both in series with the armature and main field-magnet coils, shunted around the armature and said differential series set only, substantially as set forth.

1. In an electro dynamic motor, the combination of the armature, diffcrentiz'il field-magnet coils, and cumulative field-magnet coils, both in series with the armature, main fieldniagnet coils in shunt relation to the armature, and means for varying the magnetizing effect of said differential coils, substantially as set forth.

In an cleetro-dynamic motor, the combi nation, with the armature and main field-magnet coils in shunt relation to the armature, of differential field-magnet coils and cumulative field-magnet coils, both in series with the armature, said differential coils being arranged to produce their greatest effect on diagonally-opposite parts of the magnetic field, and said cumulative coils arranged to produce their greatest effect on other diagonally opposite parts of the field, substantially as set forth.

6. In an electro-dynamic motor, the combination, with the armature of main field-magnet coils in shunt relation to the armature wound equally on all parts, of the field-magnet, and differential field-magnet coils and cumulative field-magnet coils, both in series with the armature, said differential coils being arranged .to produce their greatest effect on diagonallyoppositc parts of the magnetic field, and said cumulative coils arranged to produce their greatest effect on other diagonally-opposite parts of the field, substantially as set forth.

7. In an electro-dynamic motor, the combination of the armature, main field-magnet coils in shunt relation to the armature, differential field-magnet coils, and cumulative fieldmagnet coils, both in series with the armature, and means for varying the armaturecurrent, substantially as set forth.

This specification signed and witnessed this 28th day of I ebruary, 1887.

FRANK l. SIltAG U1.

\Vitncsses:

A. \V. KIDDLTB, I 0. ROWLAND. 

